Difference between revisions of "How to use GPIOs"
From IGEP - ISEE Wiki
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Check that user-gpio-drv.ko is currently loaded with the following command: | Check that user-gpio-drv.ko is currently loaded with the following command: | ||
<pre>lsmod</pre> | <pre>lsmod</pre> | ||
− | The result will be similar than this: | + | The result will be similar than at this: <br> |
<pre>root@localhost:~/svn.hylands.org/linux/gpio/module# lsmod | <pre>root@localhost:~/svn.hylands.org/linux/gpio/module# lsmod | ||
Module Size Used by | Module Size Used by | ||
Line 70: | Line 70: | ||
twl4030_keypad 2970 0 | twl4030_keypad 2970 0 | ||
</pre> | </pre> | ||
− | The module is loaded until system halt. | + | The module is loaded until system halt. |
=== Install dynamic library === | === Install dynamic library === |
Revision as of 16:17, 9 January 2012
Contents
Overview
This How-To is meant to be a starting point for people to learn use GPIOs for IGEP v2 devices as quickly and easily as possible. For this how-to i used Linaro Headless, Ubuntu 10.04 with Linaro Toolchain, IGEP v2 RC5 and GPIO driver wrote by Dave Hylands. There are more ways to use GPIOs in IGEP v2, but this one is very simple.
Feedback and Contributing
At any point, if you see a mistake you can contribute to this How-To.
Compile GPIO driver source code via Host
Download source code from author website using the next command:
wget -r -np http://svn.hylands.org/linux/gpio/
Due the source Makefiles are implemented for Gumstix SDK, it is necessary change some constants for compile with our Host. These constants are:
In files:
$/svn.hylands.org/linux/gpio/app/Makefile
$/svn.hylands.org/linux/gpio/lib/Makefile
Search lines:
OVEROTOP ?= /home/gumstix/overo-oe CROSS_COMPILE ?= $(OVEROTOP)/tmp/sysroots/x86_64-linux/usr/armv7a/bin/arm-angstrom-linux-gnueabi-
Replaced by your cross compiler path, for example:
OVEROTOP ?= / CROSS_COMPILE ?= $(OVEROTOP)/usr/bin/arm-linux-gnueabi-
In file:
$/svn.hylands.org/linux/gpio/modules/Makefile
Search lines:
OVEROTOP ?= /home/gumstix/overo-oe #CROSS_COMPILE ?= $(OVEROTOP)/tmp/cross/armv7a/bin/arm-angstrom-linux-gnueabi- CROSS_COMPILE ?= $(OVEROTOP)/tmp/sysroots/x86_64-linux/usr/armv7a/bin/arm-angstrom-linux-gnueabi- KERNEL_PATH ?= ../../../../../gumstix/overo-oe/tmp/sysroots/overo-angstrom-linux-gnueabi/kernel ARCH ?= arm
Replaced by your cross compiler path and your kernel source path used, for example:
OVEROTOP ?= / #CROSS_COMPILE ?= $(OVEROTOP)/tmp/cross/armv7a/bin/arm-angstrom-linux-gnueabi- CROSS_COMPILE ?= $(OVEROTOP)//usr/bin/arm-linux-gnueabi- KERNEL_PATH ?= ../../../../../<your kernel source path used> ARCH ?= arm
Go to: $/svn.hylands.org/linux/gpio/ and compile all source code downloaded using make command.
Send binaries created from Host to Igep v2.
Install binaries via IGEP
Log with root user to install binaries.
Install module
Go to:$/svn.hylands.org/linux/gpio/modules/ and insert user-gpio-drv.ko into linux kernel with the following command:
insmod user-gpio-drv.ko
Check that user-gpio-drv.ko is currently loaded with the following command:
lsmod
The result will be similar than at this:
root@localhost:~/svn.hylands.org/linux/gpio/module# lsmod Module Size Used by user_gpio_drv 1639 0 omap_wdt 3411 0 spidev 4198 0 iommu 8558 0 rtc_twl 4411 0 rtc_core 11187 1 rtc_twl twl4030_keypad 2970 0
The module is loaded until system halt.
Install dynamic library
Go to:$/svn.hylands.org/linux/gpio/lib/. libgpio.so will be found here.
If a program is link with dinamic libraries, Linux kernel find this ones in a specific paths when program is executed. Now is necessary link the libgpio.so path to the envireonment variable LD_LIBRARY_PATH, use the following commnad:
export LD_LIBRARY_PATH=/root/svn.hylands.org/linux/gpio/lib/
Check that libgpio.so is linked correctly. Go to:$/svn.hylands.org/linux/gpio/app, gpio program will be found here. Type next command:
ldd gpio
ldd command list program dependencies and show its paths. The result will be similar than this:
root@lSee if libgpio.so is found it. If you execute program in bash without linking library dependencies, bash give you a error message. ocalhost:~/svn.hylands.org/linux/gpio/app# ldd gpio libgpio.so => /root/svn.hylands.org/linux/gpio/lib/libgpio.so (0x40197000) libc.so.6 => /lib/libc.so.6 (0x401a0000) /lib/ld-linux.so.3 (0x4008a000)
Now you can execute example program gpio.
Testing driver
To make sure than driver works well, make the next test with GPIO_136 and GPIO_137:
NOTE: Make sure that MMC2_DAT4 and MMC2_DAT5 are not used, for more information visit this page. With IGEP v2 RC5 (version without WIFI) this pins are not used by default.
Configure Mux
Go to:/sys/kernel/debug/omap_mux, and change the this mux configuration:
echo 0x104>sdmmc2_dat4 echo 0x104>sdmmc2_dat5
Use cat to check it:
cat sdmmc2_dat4 cat sdmmc2_dat5
The result will be similar than this:
root@localhost:/sys/kernel/debug/omap_mux# cat sdmmc2_dat4 name: sdmmc2_dat4.gpio_136 (0x48002164/0x134 = 0x0104), b ae4, t NA mode: OMAP_PIN_INPUT | OMAP_MUX_MODE4 signals: sdmmc2_dat4 | sdmmc2_dir_dat0 | NA | sdmmc3_dat0 | gpio_136 | NA | NA | safe_mode
and
root@localhost:/sys/kernel/debug/omap_mux# cat sdmmc2_dat5 name: sdmmc2_dat5.gpio_137 (0x48002166/0x136 = 0x0104), b ah3, t NA mode: OMAP_PIN_INPUT | OMAP_MUX_MODE4 signals: sdmmc2_dat5 | sdmmc2_dir_dat1 | cam_global_reset | sdmmc3_dat1 | gpio_137 | hsusb3_tll_stp | mm3_rxdp | safe_mode
Note: OMAP_PIN_INPUT=Input and Output pin and OMAP_PIN_OUTPUT=Output pin.
Read/Write test
Link GPIO_136 and GPIO_137 with a wire, these pins are located in J990 connector with numbers 7 and 9. Type next text:
root@localhost:~/svn.hylands.org/linux/gpio/app# ./gpio input 136 root@localhost:~/svn.hylands.org/linux/gpio/app# ./gpio output 137 0 root@localhost:~/svn.hylands.org/linux/gpio/app# ./gpio get 136 0 root@localhost:~/svn.hylands.org/linux/gpio/app# ./gpio output 137 1 root@localhost:~/svn.hylands.org/linux/gpio/app# ./gpio get 136 1 root@localhost:~/svn.hylands.org/linux/gpio/app#
The text above show that driver work properly, GPIO_136 is configure like input and GPIO_137 is configure like output with value 0, now read GPIO_136 and the result is 0. To make sure configure GPIO_137 with value 1 and GPIO_136 read 1.
This driver have more options like IRQ, but is not explained here.
Under construction
Other examples:What can I do with IGEP0020#How_to_handle_the_gpio-LED.27s